Dynamic Measures based on changing data

The process is called "unpivoting"  and it is usually done in Power Query during the ETL.

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45Wcg9y9HMJcAxy9Qsx1IfTQf4uoc4hhko6SmaqQMLIAEQqALG5CYQVq4NfqxFQlaEFql4zI+L0GgNVmRiD9YJ1QJxgCdUcCwA=", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [FamilyHelper = _t, ABS = _t, Aluminium = _t, NewPreviouslyUnknownMaterial1 = _t, NewPreviouslyUnknownMaterial2 = _t, #"Polyamide " = _t]),
    #"Unpivoted Other Columns" = Table.UnpivotOtherColumns(Source, {"FamilyHelper"}, "Material", "Percentage")
in
    #"Unpivoted Other Columns"

How to use this code: Create a new Blank Query. Click on "Advanced Editor". Replace the code in the window with the code provided here. Click "Done".

That way you make the data usable for Power BI and you can accommodate any new columns in your source data.

That's just the way your sample data is encoded. Has nothing to do with your ask.  The important part is to apply the unpivot step to your actual data.

For anyone who is as thick as me; the final code i used looked like this:

let
#"Unpivoted Other Columns" = Table.UnpivotOtherColumns(MaterialMatrix,{"FamilyHelper"},"Material", "Percentage")
in
#"Unpivoted Other Columns"